1. Field of the Invention
The present invention relates to a navigation apparatus suitably mounted on an automotive vehicle for displaying a road map or the like, a navigation method and an automotive vehicle having such a navigation apparatus mounted thereon.
2. Description of the Prior Art
Various types of navigation apparatuses for use on an automotive vehicle are under development. The navigation apparatus comprises, for example, a large-capacity storage means such as a CD-ROM storing road map data, means for detecting the present position, and a display unit for displaying the road map of the neighborhood of the detected present position on the basis of the data read from the data storage means. The present position detection means includes a positioning system using a positioning earth satellite called the GPS (Global Positioning System) or a device operated using a self-contained navigation method by tracking the change in the present position from the starting point on the basis of the information including the vehicle running speed and the direction in which the vehicle is running.
Also, the map of the desired position as well as the neighborhood of the present position can be displayed on the display unit by key operation as far as the associated map data are available.
In this navigation apparatus for use on automotive vehicles, for example, the display unit is generally mounted in the vicinity of the driver's seat so that the driver can check the map of the neighborhood of the present position while the vehicle is running or waiting for a traffic signal.
The above-mentioned navigation apparatus is required to be operated in a manner not to interfere with the operation of the vehicle on which the apparatus is mounted. While the vehicle is moving, for example, complex operations of the navigation apparatus are prohibited. In other words, this navigation apparatus, when installed on the vehicle, is connected with a running condition detector (such as a parking brake switch). In this way, the apparatus can be fully operated only when the detector finds that the vehicle is stationary, and a complicated key operation is prohibited while the vehicle is not stationary (i.e., when the vehicle is moving).
It is, however, inconvenient that the key operation is impossible for switching the display map while the vehicle is moving. Demand is high, therefore, for a navigation apparatus that can be manipulated in sophisticated manner without interfering with the vehicle operation.